International Catalogue

Basic Knowledge of Fastening Technology
Basic Knowledge of Fastening Technology
Cracks in concrete
components
Cracks can occur anywhere in concrete at any time: factors involved in this are
loads like dead load, traffic or wind loads, shrinkage and creeping of the concrete
or external influences like earthquakes or ground motions resulting in tensions, deformations
and thus crack formation.
Example: in a bridge, bending occurs due to pressure forces applied to the bridge deck.
A compressive zone will occur at the top of the bridge deck, while tensile forces and
strains will occur in the lower part of the bridge deck. Concrete is not able to support
tensile loads. Steel bars, the so-called reinforcements take over this task. However, while
steel bars are capable of bearing these tensile stresses, they are stretched as they do so.
innumerable cracks are formed that are barely visible to the naked eye. This is called the
cracked tensile zone.
V-shaped
bending rack
Tension
Druck
Pressure
Cracked zone
tensile zone
Fixings suitable for cracks
With anchorings in concrete, it is almost always assumed that cracks are present
in the anchoring area that influence the bearing capacity of the fixings.
However it is very complicated, if not impossible, to prove whether the concrete
is cracked or non-cracked. For safety reasons, the use of fixings suitable for
cracks is basically recommended to designers and tradesmen. Fixings with an
approval according to ETAG 001 for cracked concrete have proved their suitability in
cracks and may thus be used without restriction in the tensile and compressive zones
of the concrete. Crack suitable fixings are also checked and approved on the basis of
American standards. These “Evaluation reports” are prepared according to ACI 318.
FZA FAZ II FHB II
SXS
▪ Due to safety reasons, always use crack suitable anchor systems such as FAZ
II, FH II, FHB II or FIS EM.
460